1. Field of the Invention
Embodiments of the invention relate to a touch sensor integrated type display.
2. Discussion of the Related Art
A touch sensor is installed in display devices such as a liquid crystal display, a field emission display, a plasma display panel, an electroluminescent display, and an electrophoresis display. The touch sensor is a kind of input device capable of receiving predetermined information or input from a user when the user touches a touch panel having the touch sensor.
The touch sensor used in the display devices may be classified into an add-on type touch sensor, an on-cell type touch sensor, and an integrated type (or in-cell type) touch sensor depending on its structure. The add-on type touch sensor is configured such that the display device and the add-on type touch sensor are individually manufactured and then the add-on type touch sensor is attached to an upper substrate of the display device. The on-cell type touch sensor is configured such that components of the on-cell type touch sensor are directly formed on the surface of the upper substrate of the display device. The in-cell type touch sensor is configured such that the in-cell type touch sensor is embedded in the display device to thereby achieve thin profile of the display device and to increase the durability of the display device.
However, because the add-on type touch sensor has the structure in which the completed add-on type touch sensor is mounted on the display device, a thickness of the display device increases. Further, the visibility of the display device having the add-on type touch sensor is reduced because of a reduction in a brightness of the display device.
On the other hand, because the on-cell type touch sensor has the structure in which the on-cell type touch sensor is formed on the surface of the upper substrate of the display device, the on-cell type touch sensor shares the upper substrate with the display device. Therefore, a thickness of the display device having the on-cell type touch sensor is less than a thickness of the display device having the add-on type touch sensor. However, the entire thickness of the display device having the on-cell type touch sensor increases because of a touch driving electrode layer, a touch sensing electrode layer, and an insulating layer for insulating the touch driving electrode layer and the touch sensing electrode layer, which constitute the on-cell type touch sensor. Further, the number of processes and the manufacturing cost in the on-cell type touch sensor increase.
The in-cell type touch sensor can address the problems associated with the add-on type touch sensor and the on-cell type touch sensor because of the advantages of the thin profile and the durability improvement. Examples of the in-cell type touch sensor include a light type touch sensor, a capacitive touch sensor, etc.
In the light type touch sensor, a light sensing layer is formed on a thin film transistor (TFT) array substrate of the display device, and it is possible to recognize light reflected by an object existing in a touched portion using light or infrared light from a backlight unit. The light type touch sensor shows a relatively stable driving performance in dark surroundings, but light stronger than the reflected light acts as a noise in bright surroundings. The light type touch sensor may erroneously recognize a non-touch operation as a touch operation even in the slightly bright surroundings because an intensity of light reflected by the actual touch operation is very weak. In particular, the light type touch sensor may not readily recognize the touch operation because an intensity of light in the surroundings exposed to solar light is strong.
Examples of the capacitive touch sensor include a self capacitive touch sensor and a mutual capacitive touch sensor. The mutual capacitive touch sensor divides a common electrode of the display device into touch driving electrode regions and touch sensing electrode regions to form mutual capacitances between the touch driving electrode regions and the touch sensing electrode regions. Hence, the mutual capacitive touch sensor measures changes in the mutual capacitances generated in a touch operation, thereby recognizing the touch operation.
In the mutual capacitive touch sensor, the common electrode is divided into a plurality of touch cells formed on the same layer, and each of the touch cells is divided into a touch driving electrode and a touch sensing electrode. As described above, because the touch driving electrodes and the touch sensing electrodes are formed on the same layer and the touch driving electrodes should not be electrically connected to the touch sensing electrodes, touch driving lines designated for connecting the touch driving electrodes to each other and separate touch sensing lines designated for connecting the touch sensing electrodes to each other are needed. For this, in the related art, the touch driving lines are formed of the same metal as gate lines when the gate lines of the display device were formed, thereby connecting the touch driving electrodes to one another in a x-axis direction. Further, the touch sensing lines are formed of metal formed on a layer different from the formation layer of the touch driving lines, the touch driving electrodes, and the touch sensing electrodes, thereby connecting the touch sensing electrodes to one another in a y-axis direction.
However, when the touch driving lines and the touch sensing lines are formed on the different layers, the design of a TFT array was complicated, and an aperture ratio is reduced due to the disposition of the touch sensing electrodes.
Accordingly, there is a need for a touch sensor integrated type display device capable of addressing the problems of the above-described kinds of touch sensors.